In many communication systems, a receiver receives signals from a transmitter over a communication channel, estimates Channel State Information (CSI) of the channel, and sends to the transmitter feedback that is indicative of the estimated CSI. The transmitter adapts the signals transmitted to the receiver based on the CSI feedback.
CSI feedback is used, for example, in Evolved Universal Terrestrial Radio Access (E-UTRA) systems, also referred to as Long Term Evolution (LTE) systems. The Third Generation Partnership Project (3GPP) E-UTRA standards specify CSI feedback for use by E-UTRA User Equipment (UE) and base stations (eNodeB). These schemes are described, for example, in 3GPP Technical Specification 36.213, entitled “Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Layer Procedures (Release 8),” (3GPP TS 36.213), version 8.6.0, March, 2009, which is incorporated herein by reference.
The description above is presented as a general overview of related art in this field and should not be construed as an admission that any of the information it contains constitutes prior art against the present patent application.